Open-cycle internal combustion engine

ABSTRACT

An open-cycle engine in which rotary power is produced by the pressure of hot gasses against confined, rotating vanes.

This application is based on provisional application U.S. Ser. No. 60/841,918, filing date Sep. 5, 2006.

FIELD OF THE INVENTION

This invention is an improved internal combustion engine of the Brayton, or open cycle type. An open cycle engine may be defined as an internal combustion engine in which the compression of air and the burning of fuel when mixed with the compressed air, takes place continuously.

Jet turbine engines that produce shaft power may best represent open cycle engines of the prior art. Engines of this type are called turbo-shaft engines, and are typically used to power helicopters and larger fixed-wing aircraft because they are efficient, lightweight, clean-burning, have a multi-fuel capability, and spin smoothly with no reciprocating parts.

BACKGROUND OF THE INVENTION

The aforementioned attributes notwithstanding, the turbo-shaft engine is not generally utilized to provide power in common conveyances such as boats, motorcars and, trucks. This is largely because a turbo-shaft engine is expensive to build, as much as ten times as expensive as reciprocating engines of the same horsepower. Additionally, the turbo-shaft engine cannot change its speed of rotation very quickly. This is because the rotating components are driven at very high speeds causing a high rotational inertia. This high rotational inertia also causes a danger when failure of a rotating component occurs, because the energy that is stored in the high speed rotating parts can be very difficult to contain.

A modern turbo-shaft engine is certainly smoother and lighter than today's dated reciprocating engines, and with the use of a regenerator, can be very efficient besides, however the acquisition and processing costs of the exotic materials needed in the turbine section push the cost of the turbo-shaft engine well out of reach for most applications. The use of a regenerator adds even more bulk and cost to the system.

In a turbo-shaft engine, the hot gasses of combustion are required to enter the turbine power section at near-sonic speeds. These near-sonic gas speeds are required to produce meaningful power. Unfortunately, the high velocity of the hot gasses causes a major energy loss due to friction and turbulence, with the parasitic friction loss increasing generally as the square of the velocity.

The aforementioned near-sonic gas speeds are required because the gasses must impinge the initial rows of turbine blades at very high velocities to provide a meaningful kinetic energy force to the blades. Subsequent rows of blades produce power using a reaction force that can be compared to the lift produced by air flowing over an aircraft wing. These rows of blades also require a high velocity in the hot gasses. Both the impingement forces and the reaction forces increase greatly with an increase in the speed of the hot gasses. For this reason, turbine engines are designed to use as high a gas velocity as possible—just below the velocity that would cause detrimental sonic shock waves to form. Again, there is a substantial energy loss due to the turbulence and parasitic drag caused by these high gas speeds.

Also in the turbine type of power section, the tremendous turbulence caused by the high gas speeds and the vectoring of hot gasses from blade to blade, causes a substantial transfer of heat to the power section components, requiring that they be fabricated from exotic, high temperature materials in order to have adequate strength.

In contrast, the present invention, an improved open cycle internal combustion engine, does not utilize a turbine power section. The present invention instead uses the pressure of hot gasses against confined, rotating vanes to produce power, and therefore does not require the ultra-high gas velocities that are needed in a turbine. The lower speed of hot gasses in the power section of the present invention, provides a huge reduction in parasitic drag when compared to a turbo-shaft engine, resulting in a greater economy of operation. The reduced speeds of the hot gasses, and the absence of blade-to-blade vectoring provides a reduction in turbulence that also reduces heat transfer from the hot gasses to the metal parts of the power section, providing a greatly reduced requirement for exotic high temperature materials.

A reduced speed of hot gasses is made possible in the present invention by the use of a unique and efficient counter-rotating rotor system to extract power, rather than the turbine found in a turbo-shaft engine. This dual rotor system provides a substantially positive containment of the hot gasses of combustion during the power-producing portion of a cycle. In comparison, the gasses flow relatively freely through the blades of a turbine type of power section, losing useful energy in turbulence and drag as they are vectored from blade to blade. Rotational power in the present invention is produced mainly by the pressure of hot gasses against the surfaces of confined rotating vanes, rather than by the kinetic and reactive forces utilized in a turbine. This eliminates the need for ultra-high gas velocities with the resultant high amounts of energy loss and heat transfer.

The present invention utilizes the hot, pressurized gasses of combustion, produced by any of a multitude of different fuels, to apply a pressure force to the surfaces of vane protrusions on counter-rotating rotors that rotate within a closely confining encasement. The surfaces of the vanes opposite to the surfaces on which the pressure force is applied are in gaseous communication with the atmosphere via an exhaust port, and the resultant pressure differential provides the force to turn the rotors.

The hot gasses change direction smoothly and infrequently in the power section of the present invention, as opposed to the significant number of vector changes found in a turbine power section. This ease of gas movement provides a reduced amount of drag and turbulence and helps to provide a dramatic increase in efficiency over the turbo-shaft engine.

As previously mentioned, the turbo-shaft engine is available only at a very high cost, which limits its use to military and commercial aircraft, military conveyances such as tanks and ships, and large electrical power plants, where the costs of acquisition and the provision of regeneration is not so much at issue. In addition to the high cost of the exotic materials required in the turbo-shaft engine, additional costs are incurred due to the turbo-shaft engine's high rotational speeds, which require special bearings and lubrication systems, with no tolerance for error in manufacturing.

In contrast, the power section of the present invention has relatively low rotational speeds, reducing the requirement for special bearings and lubrication systems. Additionally, the low rotational inertia present at low speeds of rotation allows speed changes to be effected much more easily and quickly when compared to the turbo-shaft engine. As in a turbo-shaft engine, speed changes in the present invention are accomplished by reducing the amount of fuel metered to the engine. When extremely rapid changes in rotational speed are required, additional throttling of the intake air may be effected.

The present invention is simple in structure, with little requirement for exotic metals. These traits help make it considerably less expensive to manufacture than a turbine engine, and because it has few moving parts, it can also be significantly less expensive to manufacture than a reciprocating engine. This low cost of manufacture along with an unprecedented efficiency that is inherent in the design, allows an opportunity for wide-spread use in automobiles (especially the hybrid type of automobile), boats, trains, airplanes, electrical generators, and other usages in which a simple, low cost, highly efficient, clean burning, multi-fuel engine can be of service.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide an open cycle internal combustion engine with an increased fuel efficiency over open cycle engines of the prior art, reducing emissions and lowering operating costs.

Another object of the present invention is to provide an open cycle internal combustion engine that is less complex in fabrication than open cycle engines of the prior art, easing manufacture, and lowering acquisition costs.

An additional object of the present invention is to provide an open-cycle internal combustion engine in which heat transfer to the power section components is less than open cycle engines of the prior art, reducing the need for exotic, heat resistant metals, and their attendant manufacturing complexity and cost.

Another object of the present invention is to provide an open-cycle internal combustion engine for general use that can run cleanly, efficiently and safely on a wide range of different fuels.

These, and other objectives are achieved in the present invention, which extracts power from the pressure of hot gasses of combustion. The pressure of hot gasses is applied to the surfaces of vanes that are integral with, or rigidly coupled to counter-rotating rotors, rotating within a closely confining encasement. The use of confined rotating vanes to provide power allows a substantial reduction in the speed of the hot gasses relative to the metal parts of the power section when compared to a turbine power section. This reduction in speed greatly reduces drag, a product of the square of the speed, which substantially increases efficiency. Slower gas speeds also result less heat transfer to the metal parts of the power section, which is represented by a lower film co-efficient in the heat transfer equation. This equation shows that lowering the speed of the hot gasses results in a substantial reduction of the amount of heat transferred into adjacent parts. Lowering the amount of heat transfer, reduces or eliminates the need for exotic heat-resistant metals and their attendant manufacturing costs.

Additional cooling of the components in the power section of the present invention, takes place due to the expansion and resultant cooling of the hot gasses during the part of the cycle that the gasses are released through the exhaust port into the atmosphere. The portions of the vanes and rotors that are in gaseous communication with these expanding gasses are provided cooling by the expanding gasses. In comparison, the turbine parts in a turbo-shaft engine are continuously exposed to high-speed hot gasses, and there is little cooling of the turbine components that can be attributed to expanding gasses.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 1A show cross-sections of an embodiment of an open cycle internal combustion engine of the present invention. A gear-driven centrifugal air compressor 1 provides compressed air through a compressed air duct 2 to a plenum 4 for admittance through a burner liner 9 in which the compressed air is mixed with fuel and ignited so that combustion takes place. A centrifugal air compressor is used in this embodiment because of its high efficiency, however other types of air compressors, including an embodiment of the mechanism that extracts power from the burning gasses of the present invention, could be used as well. After ignition of the compressed air and fuel, resulting hot gasses of combustion provide pressure to integral hollow vanes 19 of dual counter-rotating rotors 13 with integral vane follower cavities 16 that counter-rotate at a 1:1 ratio within a rotor encasement 3.

The compressor 1 also provides cooling bleed air to the hollow rotor shafts 21 by way of the rotor shaft ducts 34 to cool the rotors and vanes. The rotor gears 28 ensure that both rotors counter-rotate at the same speed, so that the tips and adjacent surfaces of the hollow vanes 19 can follow the contours of the surfaces of the vane follower cavities 16 with substantial precision. The closeness of surfaces of the hollow vanes 19 to the surfaces of the vane follower cavities 16, prevents any substantial leakage of combustion gasses between said surfaces, during the portion of the cycle that the surfaces of the hollow vanes follow the surfaces of the vane follower cavities. During the remainder of the cycle, combustion gasses are substantially prevented from escaping between the rotors 13 by the closeness of the surfaces of the outside diameters of the rotors. Leakage between the sides of the rotors 31, and the inner surfaces of the sides of the rotor encasement 3 is also substantially prevented by the closeness of said surfaces. Leakage of hot gasses between the tips of the hollow vanes 19 and the inside contours 9 of the rotor encasement 3 is substantially prevented by the closeness of their surfaces. Labyrinth or other types of seals may augment some of the areas of closeness in which leakage of hot gasses might occur. Power may be taken from drive gears 29 that are connected to the rotor shaft 21.

FIG. 2 shows a cross section of another embodiment of the present invention having counter-rotating rotors 13 and 11. There are two solid rotor vanes 12 fixedly attached to rotor 13. The vane follower rotor 11 contains the vane follower cavity 16 and is geared to rotor 13 in a 2:1 ratio, which drives the vane follower rotor 11 at twice the speed of rotor 13. Hot gasses of combustion are substantially prevented from leaking between the vane follower rotor 11 and the vane follower rotor case contour 22 by a closeness in tolerance between the two. Again, labyrinth or other types of seals may augment some areas of closeness in which leakage of hot gasses might occur. There is one vane follower cavity in this embodiment, however other embodiments could provide a vane follower rotor having two or more vane follower cavities and be driven at speeds other than 2:1 to allow the vane follower cavities to follow in concert with the rotor vane or vanes. The rotor vanes 12 are not hollowed for cooling in this embodiment, but are instead cooled by conduction into the material of the rotor 13. The material of the rotor is in turn cooled by providing the rotor cavities 10 with a cooling fluid that may be liquid or gas, through a cooling duct 15 in the side case. The vane follower rotor 11 may also be hollowed for cooling.

FIG. 3 shows a cross section of another embodiment of the present invention, the dual rotors 13, having integral vane follower cavities 16. As in FIG. 2, the rotor vanes 12 are not hollowed for cooling, but are instead cooled by conduction into the material of the rotors 13 and by the expansion of hot gasses at the low-pressure side of the vanes. The rotors 13 are hollowed so that cooling fluid introduced through cooling ducts 15 at the side of the engine casings may pass through the rotor cavities 10.

In this embodiment, compressed air for combustion is provided by a turbocharger 37 powered by residual hot gasses from the exhaust duct 14. The turbocharger in this embodiment is of the radial inflow type with a centrifugal compressor, however other types of turbochargers or compressors may be used as well.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1 and 1A show cross-sections of the preferred embodiment of an open cycle internal combustion engine of the present invention. The FIG. 1 section is taken on a line through the mid-point of the rotors 13, combustion chamber liner 9, and plenum 4. The rotor shaft plugs 23, shown in FIG. 1A, are not depicted in this view. The FIG. 1A section is taken on a line taken longitudinally through the centers of the hollow rotor shafts.

In operation;

A centrifugal compressor 1, driven by a drive gear 29 on one of the rotor shafts 21, forces compressed air through a compressed air duct 2 and into a plenum 4. The plenum 4 transfers the compressed air to a burner shroud 8, which conducts the compressed air to a swirler 7, and a burner liner 9. Fuel is introduced into the combustion area by a fuel-metering nozzle 6, which is fed by a fuel-metering pump, which is of conventional design and not shown. The swirler creates turbulence to mix the compressed air homogeneously with the fuel, which may be a liquid, solid particulate, or gas.

The fuel-air mixture is ignited inside the burner liner by an igniter 5 and is further mixed with the compressed air entering the burner liner through air metering holes 30. The resulting expanding hot gasses of combustion provides pressure to the hollow vanes 19 which are integral with the rotors 13, that turn counter-rotationally at a speed that even under load is fast enough to allow enough of the pressure of combustion inside the burner liner to be released to ensure that the pressure inside the burner liner is always slightly lower than the pressure of the compressed air outside the liner, so that burning gasses do not bleed back through the metering holes 30.

The rotors 13, which are identical in diameter in this embodiment, turn counter-rotationally in a precise 1:1 ration due to a pair of rotor gears 28 which are fixedly connected to rotor shafts 21. The rotors turn in the directions shown by the arrows around the rotor peripheries in FIG. 1 that depict burning gasses. The pressurized hot gasses are substantially prevented from leaking between vanes 19 and the vane follower cavities by the closeness of the surfaces of the vanes 19 to the surfaces of the vane follower cavities 16 during the portion of rotation in which they are in proximity. Vane and vane follower cavity shapes other than those shown may also be useful, as long as the surfaces of the vanes and vane follower cavities remain in close proximity during the part of the cycle that the vane sweeps through the vane follower cavity. The gasses are substantially prevented from leaking between the rotors by the closeness of the outside diameters of the rotors 13 at all other times during the cycle.

Pressurized hot gasses are substantially prevented from leaking between the tips of the vanes 19, and the internal engine case contours 35 by the closeness between said parts. Pressurized hot gasses are also substantially prevented from leaking between the sides of the rotors 31 and the inner sides of the engine cases 3 by a closeness between said parts. The surfaces of the sides of the rotors 31 and the sides of the engine case sides 3 are depicted as flat in this embodiment for ease of fabrication, however to provide a lighter weight, said rotor and engine case sides could also be convex and concave respectively, or vice-versa, so that the engine case sides could providing a higher strength to resist the pressure of the hot gasses, while weighing less. Labyrinth or other types of seals may be used in any or all of the areas of close proximity to provide additional sealing of leakage of the combustion gasses.

The rotor shafts 21 are supported by rotor shaft bearings 26, which are ball bearings in this embodiment, however the bearings could also be of the plain or roller type. Oil for lubrication is pumped to the bearings through oil feed tubes 24 by an oil pump of conventional design that is not shown. The oil flows to, or is sprayed on the rotational parts of the bearing, and is contained within the bearing housing 36 by bearing seals 27. Pressure from the compressor bleed air may be applied to the cavity between the innermost of the bearing seals 27 and the engine cases 3, through seal cavity ports 36 to prevent hot gasses from leaking through to the seals. Excess oil is returned by way of the oil return tubes 25 to an oil cooler and sump of conventional design, which are not shown.

The rotors 13, rotor shafts 21, rotor vanes 19, and vane follower cavities 16, are cooled by compressor bleed air that is introduced to the hollow rotor shafts 21 through the bleed air intake ports 34. Other pumping means and other fluids may be used for cooling as well, such as water cooling, The hollow rotor shafts have rotor shaft plugs 23 at their middle, to force air through a plurality of rotor shaft ducting holes 18 on the air entrance side of the rotor shaft plug for the purpose of cooling the internal walls of the rotors, vanes, and vane follower cavities. The air absorbs heat from the rotors, vanes, and vane follower cavities, and then exits through rotor shaft ducting holes 18 on the air exit side of the rotor shaft plug 23.

Compressor bleed air is piped to the bleed air intake ports 34 from the bleed air exit tubes 33 that are in gaseous communication with the plenum 4 by air duct piping that is not shown. The rotor vanes 19 have rotor vane bleed holes 17 to help cool the tips of the vanes, and the engine case contours 35. The cooling requirements may be reduced with the use of insulating ceramic or other high temperature coatings in the areas that are exposed to hot gasses.

Rotational power may be taken from the engine using one or both of the drive gears 29. Said rotational power may alternately be taken from one or both of the enmeshed rotor gears 28 as could power be taken to drive the compressor, in which case one or both of the drive gears 29 could be eliminated. 

1. An open-cycle internal combustion engine, comprising; an air compressor, a burner, a metering means to admit fuel to said burner, a mixing means to mix compressed air and fuel in said burner, an ignition means to ignite the mixture of compressed air and fuel in said burner, and a power extraction means to extract power from the resultant burning gasses, said power extraction means comprising; a rotors encasement, an intake port in gaseous communication with the cavity of said rotors encasement, an exhaust port in gaseous communication with the cavity of said rotors encasement, a first rotor of substantially cylindrical shape having at least one vane protrusion longitudinally aligned with said first rotor, with the option of having at least one vane follower cavity longitudinally aligned with said first rotor, a second rotor of substantially cylindrical shape having at least one vane follower cavity longitudinally aligned with said second rotor, with the option of having at least one vane protrusion longitudinally aligned with said second rotor, a shafting means at the center of said first rotor, a shafting means at the center of said second rotor, bearing means attached to said shafting means of the first rotor and bearing means attached to said shafting means of the second rotor, said bearing means providing a rotational coupling between said shafting means of the first rotor and the rotors encasement, and between said shafting means of the second rotor and the rotors encasement, sealing means to prevent lubricant that may be used in the bearing means from escaping from said bearing means, gearing means fixedly attached to said shafting means of the first rotor, and gearing means fixedly attached to said shafting means of the second rotor, with said gearing means on the shaft of the first rotor, and said gearing means on the shaft of the second rotor, enmeshed to effect a counter-rotationary movement between said first rotor and said second rotor within the rotors encasement, so that the vane protrusion(s) and the vane follower cavity(s) of the rotors come to a precise proximity during the times of the cycle that the counter-rotationary gearing rotates them into proximity.
 2. The engine described in claim 1, wherein the first rotor and the second rotor of the power extraction means are equal in length and aligned lattitudinally and longitudinally within the rotors encasement.
 3. The engine describing in claim 1, wherein the cylindrically shaped portions of the external surfaces of the first rotor, and the cylindrically shaped portions of the external surfaces of the second rotor, are held in a closeness of proximity by the spacing of the bearing means within the rotors encasement, said closeness of proximity for the purpose of minimizing the leakage of pressurized hot gasses between said cylindrically shaped portions of the external surfaces of said first rotor, and said cylindrically shape portions of the external surfaces of said second rotor, during the times of the cycle that said cylindrically shaped portions of the external surfaces of said first rotor, and said cylindrically shaped portions of the external surfaces of said second rotor are in proximity.
 4. The engine described in claim 1, wherein a length of the external surface of the vane protrusion of the first rotor and a length of the external surface of the vane cavity of the second rotor move in a closeness of proximity during the times of the cycle in which said length of the external surface of the vane protrusion of said first rotor and said length of the external surface of the vane follower cavity of said second rotor are in proximity, said closeness of proximity for the purpose of minimizing the leakage of pressurized hot gasses between said length of the external surface of the vane protrusion of the first rotor and said length of the external surface of the vane follower cavity of the second rotor.
 5. The engine described in claim 1, wherein the length of the outermost surface of a vane protrusion moves in a closeness of proximity to a length of a cylindrically contoured inner surface of the rotors encasement, during the times of the cycle when said length of the outermost surface of a vane protrusion and said length of a cylindrically contoured inner surface of the rotors encasement are in proximity, said closeness of proximity being for the purpose of minimizing the leakage of pressurized hot gasses between said length of the outermost surface of a vane protrusion and said length of a cylindrically contoured inner surface of the rotors encasement.
 6. The engine described in claim 1, wherein the surfaces of the sides of the rotors, which includes the surfaces of the sides of the vane protrusions and the surfaces of the sides of the vane follower cavities, move in a closeness of proximity to the inner surfaces of the sides of the rotors encasement, said closeness of proximity being for the purpose of minimizing the leakage of pressurized hot gasses between said surfaces of the sides of the rotors, which includes the sides of the vane protrusions and vane follower cavities, and said inner surfaces of the sides of the rotors encasement.
 7. The engine described in claim 1, wherein some or all of the parts including the first rotor, second rotor, shafting means, rotors encasement and vanes are hollowed to allow the flow of a fluid for cooling.
 8. The engine described in claim 1, wherein a vane may be integral with to the rotor, or separate and fixedly attached to said rotor.
 9. The engine described in claim 1 wherein a vane follower cavity may be integral to the rotor, or separate and fixedly attached to said rotor.
 10. The engine described in claim 1 wherein the shafting means of the rotors may be integral to the rotor, or separate and fixedly attached to said rotors.
 11. The engine described in claim 1 wherein the gearing means that provides counter-rotationary movement to the rotors may be on one side only, or on both sides of the rotors.
 12. The engine described in claim 1 wherein compressor bleed air is admitted between the sealing means of a bearing, and the engine cases so that the hot gasses of combustion, which are at a lower pressure than the compressor bleed air, cannot leak through the spacing between the shafting means of the rotors, and the engine cases.
 13. A mechanism comprising the power extraction means of the engine described in claim 1, when driven in reverse through one or both of the shafting means, can be used as an air compressor, or as the air compressor for the engine described in claim
 1. 14. The engine described in claim 1 wherein rotary power can be taken from one or both of the shafting means of the rotors. 